I have had Atari computers at home since 1990. In fact, one Atari or other has always been the only computer in the house. Beside being quite useful at times to do some serious work, meddling with Ataris was, and still is, a nice hobby- something like driving an oldtimer car.
These are some of my works related to the 16bit line of Atari computers:
HD-Floppy module :   Schematics, PCB layout and instructions for building and installing a simple one-chip HD-floppy module into ST and MegaST range of computers. An interesting feature of this particular design is that it switches the floppy-controller chip into 16 MHz mode only when a HD-floppy is inserted into drive, thus preventing needless overheating of the overclocked WD1772 chip. Instructions for physical installation of the device in the computer are included.
LaceScan board :   An implementation of Ulf Ronald Andersson's LaceScan (c), a two-chip hardware hack which increases screen resolution of Atari ST and MegaST computers up to about 750x490 on an appropriate monitor (maximum of about 688x480 possible on a well-adjusted SM-124). The work presented here consists only of a PCB design and instructions for installing it in Atari MegaST computers. Schematics and other details of LaceScan can be found at Ulf Ronald Andersson's web page: http://dlanor.atari.org
Floating-point accelerator :   Schematics, prototype board layout and instructions for building and installing a memory- mapped MC66881 Floating Point Unit board into MegaST (or Atari ST) range of computers. For the few applications which recognize this type of FPU it gives an average performance boost of about 500% in floating-point-intensive operations.
Tera Desktop :   The only open-souce desktop currently available for the 16-bit and 32-bit lines of Atari computers. A small, fast and simple desktop suitable for the modern multitasking environments but also capable of running on the low-end machines.